The present invention relates to a wellhead assembly including tubing hanger and, more specifically, to positioning a ball valve in fluid communication with the annulus bore of a tubing hanger of an oil or gas well production system. The improved tubing hanger may be used in surface or subsea trees, and may be used in either conventional or horizontal trees.
A conventional tubing hanger in a wellhead assembly has a vertical production bore and at least one generally vertical annulus bore which is in communication with the tubing annulus between the production tubing and the production casing. The lower end of the annulus bore thus exits the bottom of the tubing hanger, and in a conventional tree or a single-bore tree the upper end of the annulus bore typically exits the top of the tubing hanger for communication with the tree. In a horizontal tree, the well annulus is typically in communication with a lateral bore in the tree housing, which in turn may be connected by a crossover line to a crossover valve, thereby allowing annulus fluids to flow laterally out of the tubing hanger and through the tree body.
The annulus bore in subsea trees has conventionally been opened and closed by a gate valve. Gate valves require a large area for installation and operation. Because room in the tubing hanger must also be provided for various penetrations, such as control lines, gate valves in tubing hangers are not preferred. U.S. Pat. No. 5,706,893 discloses a gate valve which requires a complicated operator or actuator which relies upon gears, which are not suitable for use in subsea wells. A gear-type actuator for a rotary shear seal valve in the annulus line of the tubing hanger is prone to clogging with debris, thereby further reducing reliability. U.S. Pat. No. 4,807,700 disclose another gear-operated ball valve in the annulus of a tubing hanger.
U.S. Pat. No. 6,176,316 discloses a ball valve in the producing fluid bore of a tubing hanger with an external operator. External actuators cannot be retrieved for repair or replacement with the tubing hanger, and the size of the operators add significant length and cost to the tree system.
U.S. Pat. No. 5,769,162 discloses a sleeve valve in the annulus bore of a tubular hanger. Sleeve valves have a tortuous flow path which is undesirable, and seals in a sleeve valve are prone to getting damaged as they pass over the lateral entry port in the valve. U.S. Pat. No. 5,305,230 discloses an annulus slide valve in a tubing hanger. U.S. Pat. Nos. 5,143,158 and 5,687,794 disclose annulus lines in a tubing hanger.
U.S. Pat. No. 5,873,415 discloses a ball valve within the annulus line of a subsea test tree. The ball valve is biased closed by a spring, so that when hydraulic pressure is removed, the valve will automatically close. When a valve is provided in a tubing hanger, the valve should be a xe2x80x9cfail-as-isxe2x80x9d type, so that the valve retains the position in which it was last moved, whether opened or closed. Once moved to that position, fluid pressure may be removed, and the valve will remain in the last moved position. U.S. Pat. No. 6,227,301 discloses two ball valves in series in a subsea test tree each in fluid communication with a production string, with another valve in one annulus bore operated by an umbilical from the surface, and a cable to power an electrical submersible pump in another annulus bore.
U.S. Pat. No. 3,601,190 discloses a ball valve in the production string of a hanger. The valve is accordingly for production control, rather than for annulus control. A sleeve is provided only partially around the ball, and the ball moves up and down axially when it is opened and closed, which may cause pressure build up when the ball is actuated. The ball valve is spring return closed. Internal producing fluid pressure may actuate the ball valve between the opened and closed positions.
U.S. Pat. No. 6,109,353 discloses a ball valve in a test tree or riser joint which is spring return closed. U.S. Pat. Nos. 5,992,527, 5,865,246 and 5,535,826 also disclose a ball valve in a tree. U.S. Pat. No. 6,062,314 discloses a ball valve.
The disadvantages of the prior art are overcome by the present invention, and an improved tubing hanger is hereinafter disclosed with a ball valve positioned in communication with the annulus bore in the tubing hanger.
A tubing hanger is disclosed for use in an oil or gas well for suspending tubing weight from a wellhead housing. The tubing hanger includes a production bore, at least one annulus bore, a valve open inlet port and a valve closed inlet port. The annulus bore is in fluid communication with an annulus about the tubing string. A ball valve preferably may have a generally straight through bore with an axis generally aligned with the axis of the annular bore. An actuator sleeve surrounds the ball and acts as a hydraulic piston. The actuator sleeve is moveable axially only in response to the application of hydraulic pressure to the valve open or valve closed inlet ports, which are isolated from the annulus and production bores. Axial movement of the actuator sleeve causes the ball to rotate from an open position to a closed position. The release of hydraulic pressure causes the actuator sleeve and the ball valve to remain in last position to which it was moved. The ball valve in the annulus bore may be moved to a closed position to shut off flow during setting of the tubing hanger, and may subsequently be opened for testing and circulation.
It is an object of the present invention to provide an improved tubing hanger with a ball valve in communication with the annulus bore for sealing the bore when the ball valve is closed, and for opening the bore for testing and circulation operations. A related object of the invention is to provide a wellhead assembly including the improved tubing hanger.
It is a feature of the present invention that the wellhead assembly with the tubing hanger having a ball valve in the annulus bore may be used in a conventional or single-bore tree, wherein flow lines from the ball valve pass upwards to the top of the tubing hanger. It is a further feature of the invention that the wellhead assembly with the tubing hanger having a ball valve in the annulus bore may be used in a horizontal tree wherein the tree housing includes a lateral port in fluid communication with the production bore. The ball valve may be closed when a tubing hanger running tool and/or a work-over riser is in place.
A significant feature of the tubing hanger with a ball valve in the annulus bore is that the ball valve and its actuation mechanism are positioned inside the primary pressure barrier, i.e., inside the seal, such as the DX gasket, on the wellhead or the tree. Since the ball valve is positioned within the tubing hanger, it is immune to being knocked off, e.g., due to dropped objects. The ball valve requires much less room than a gate valve, thus leaving more room in the tubing hanger for penetrators and control lines. The ball valve actuating mechanism is relatively simple and highly reliable.
Another significant feature of a tubing hanger according to the present invention is that the actuator sleeve seals fluid pressure in the annulus bore, and accordingly housings and seals external of the actuator sleeve are not required to close off the annulus bore. An upper seal may be provided along the actuator sleeve above the ball valve for sealing with the tubing hanger body, and a lower seal provided below the ball valve also seals with the tubing hanger body while the actuator sleeve moves between opened and closed positions.
It is a further feature of the invention that a production control valve external of the tubing hanger body be provided for controlling fluid flow in the production bore.
Another significant feature of the invention is that the ball valve is preferably positioned within the tubing hanger body. The ball valve is normally closed, and is conventionally opened for a work-over or crossover operation. The ball valve is moveable between opened and closed positions only in response to fluid pressure from the valve open inlet port or the valve closed inlet port. The ball valve is preferably rotated between opened and closed positions about an axis stationary with respect to the tubing hanger.
Another significant feature of the present invention is that the ball valve may form a straight-through flow path when the valve is open. By providing a ball valve with a straight-through flow path, erosion on the valve is minimized when high velocity fluids pass through the valve.
These and further objects, features, and advantages of the present invention will become apparent from the following detailed description, wherein reference is made to the figures in the accompanying drawings.